[Application of optical coherence tomography in the assessment of the posterior lens capsule during anti-angiogenic therapy]. / Primenenie opticheskoi kogerentnoi tomografii v otsenke zadnei kapsuly khrustalika na fone provedeniya antiangiogennoi terapii.

Intravitreal injection (IVI) of anti-angiogenic drugs is one of the most common therapeutic procedures in ophthalmology. In recent years, a new non-contact study method has been developed - anterior segment optical coherence tomography (AS-OCT), which allows the formation of three-dimensional images of the lens and provides more detailed information about its structure and morphology. PURPOSE: This study uses optical coherence tomography method to analyze the risks of developing changes in the posterior lens capsule in patients after IVI of an anti-angiogenic drug. MATERIAL AND METHODS: The study involved 100 people (14 men and 86 women) with a natural lens and neovascular age-related macular degeneration (nAMD). The average age was 70.57±7.98 years. During the study (12 months), all patients underwent IVI of an anti-angiogenic drug aflibercept in the treat-and-extend (T&E) mode. All subjects were divided into 2 groups: with a total number of IVI less than 10 - group 1 (50 patients), and more than 10 IVI - group 2 (50 patients, of which 49 were included in the study). All patients underwent OCT using the Optopol REVO NX device (Poland) with the Anterior B-scan Wide protocol before inclusion in the study, as well as after 3, 6 and 12 months. RESULTS: It was found that the risk of developing a posterior lens capsule rupture, visualized using OCT, depends on the total number of IVI (correlation coefficient 0.473 p=0.001): the more IVI, the higher the probability that damage to the posterior capsule will occur after the next IVI, and after the 15th injection the risk of developing damage to the posterior capsule increases sharply. CONCLUSION: The astudy analyzed the risk factors for the development of posterior lens capsule damage that can be detected using OCT, and presented three risk groups for the development of rupture (or damage) of the posterior lens capsule depending on the number of intravitreal injections performed.

[Effectiveness of anti-VEGF therapy for neovascular age-related macular degeneration in different types of exudative fluid localization]. / Effektivnost' anti-VEGF-terapii neovaskulyarnoi formy vozrastnoi makulyarnoi degeneratsii pri razlichnykh tipakh lokalizatsii ekssudativnoi zhidkosti.

PURPOSE: To assess the effectiveness of anti-VEGF therapy in different types of fluids localization in neovascular age-related macular degeneration (AMD). MATERIAL AND METHODS: The study included 16 people (16 eyes) with exudative AMD. The study included patients with fibrovascular detachment of the retinal pigment epithelium (RPE), subretinal and intraretinal fluid. The patients were divided into two groups: in the first group, fibrovascular RPE detachment was combined with subretinal fluid (9 eyes); in the second group, fibrovascular RPE detachment was accompanied by both sub- and intraretinal fluid (7 eyes). All patients underwent standard ophthalmological examination, which included visometry, biomicroscopy, and ophthalmoscopy under conditions of drug-induced mydriasis. Additionally, OCT of the macular region and OCT-angiography were performed. RESULTS: Over the entire observation period, the first group of patients received an average of 5.11 intravitreal injections (IVI), the second group - 5.14 IVI. Visual acuity was comparable in both groups at the beginning of the study. Subsequently, the treatment resulted in an increase in visual acuity after 3 months in the first (p=0.066) and second (p=0.043) groups, as well as after 12 months in both groups (p=0.043). In the first group of patients, after 12 months, an increase in RPE detachment was observed (p=0.942), which suggests that the disease activity remains underestimated on OCT when RPE detachment and subretinal fluid are combined. In the first group, complete resorption of subretinal fluid occurred in 2 people. In the second group, resorption of subretinal and intraretinal fluid occurred in 6 people. CONCLUSION: Regardless of the subtype of fluid, anti-VEGF therapy is an effective method for treating exudative AMD. Intravitreal injections are necessary both in the presence of intra- and/or subretinal fluid, and fluid under RPE. The greatest difficulty is assessment of the fluid under the RPE.

[Real clinical practice of antiangiogenic therapy in patients with age-related macular degeneration. Retrospective analysis of functional results]. / Real'naya klinicheskaya praktika primeneniya antiangiogennoi terapii u patsientov s vozrastnoi makulyarnoi degeneratsiei. Retrospektivnyi analiz funktsional'nykh rezul'tatov.

PURPOSE: To assess the functional results of antiangiogenic therapy in patients with exudative form of age-related macular degeneration (AMD) in real clinical practice. MATERIAL AND METHODS: The study included 90 people (90 eyes) with active choroidal neovascularization (CNV) on the background of AMD. All patients were divided into 6 groups depending on the year of treatment - from 2013 to 2018, all patients were divided into 6 groups and overall the retrospective study sited at Research Institute of Eye Diseases (Moscow) lasted 8 years. All patients underwent standard ophthalmological examination including visometry, biomicroscopy and ophthalmoscopy under drug-induced mydriasis, as well as optical coherence tomography, fundus angiography and OCT-angiography. RESULTS: According to the results of the analysis of OCT data obtained from 2013 to 2017, among all patients with exudative AMD, patients with types I and II of CNV and single patients with RAP prevailed, which explains the high visual acuity - about 0.5 - in all groups after the start of the treatment (table 1 and 2). In 2018, 33.3% of patients were diagnosed with RAP (the same number of eyes as with types I and II of CNV), which can be explained by the introduction of OCT-angiography into wide clinical practice. The lack of increase in visual acuity is most likely associated with a small amount of intravitreal injections (IVI) - 4.8 IVI in the first year and 3.3 IVI in the second injection year. In patients who received more than three IVI in the first year of observation, visual acuity increased from 0.49±0.03 to 0.6±0.03 (p=0.04), in the case of less than three IVI in the first year, visual acuity was not changed, amounting to 0.42±0.1 before and 0.44±0.1 (p=0.655) after the treatment. CONCLUSIONS: Patients of all groups exhibited proportional stabilization of visual acuity, a decrease in the thickness of the retina and total macular volume. The lack of improvements of visual acuity is most likely associated with a small amount of IVI.

[Conjunctival microflora and its antibiotic sensitivity after serial intravitreal injections]. / Mikroflora kon''iunktivy i ee chuvstvitel'nost' k antibiotikam posle mnogokratnykh intravitreal'nykh in''ektsii.

INTRODUCTION: The approach to post-procedure management of patients undergoing intravitreal injections should be unified and consistent. Frequent use of antibiotic drugs leads to generation of resistant conjunctival strains. PURPOSE: To study the composition of conjunctival microflora and its antibiotic susceptibility in patients who received 20 or more intravitreal injections and concomitant antibiotic therapy, and in a group of patients of the same age without history of intravitreal injections or ophthalmological operations. MATERIAL AND METHODS: A total of 40 inoculations were performed (20 patients in each group, 40 eyes). In case of culture growth, species identification and antibiotic sensitivity of the microorganisms were investigated using automated identification and susceptibility testing system BD Phoenix 100. RESULTS: Culture growth was observed in 70% of the control group patients. All isolated microorganisms were different types of staphylococci - Staphylococcus epidermidis (78.57%), S. caprae (7.14%), S. hominis (7.14%), and S. aureus (7.14%). In the second group, we observed culture growth in 55% of cases. Eleven cultures were Gram-positive bacteria: S. epidermidis (72.73%), S. haemolyticus (18.18%), S. aureus (9.09%). Gram-negative Pseudomonas aeruginosa was detected in 1 patient. In the control group, multi-resistant cultures accounted for 42.86%. In the group of patients with multiple intravitreal injections, 75% of cases showed multiresistance (9 out of 12 isolates). In the group of patients who have undergone 20 or more injections, greatest resistance was observed to penicillin G, doxycycline, gentamicin, erythromycin, clindamycin, moxifloxacin, fusidic acid, chloramphenicol, and trimethoprim/sulfamethoxazole compared to the control group. CONCLUSION: Overuse of antibiotics in the management of patients receiving intravitreal injections leads to selection of resistant strains.

[Electrophysiological study of the visual pathway in anti-VEGF therapy of neovascular age-related macular degeneration combined with glaucoma]. / Élektrofiziologicheskoe issledovanie zritel'nogo puti pri anti-VEGF-terapii neovaskuliarnoi vozrastnoi makuliarnoi degeneratsii v sochetanii s glaukomoi.

PURPOSE: To assess the effect of intravitreal administration of anti-VEGF drugs ranibizumab and aflibercept on the functional state of the visual pathway in patients with neovascular age-related macular degeneration (nAMD) and primary open-angle glaucoma (POAG) using the method of recording visual evoked potentials (VEP). MATERIAL AND METHODS: A total of 54 patients (54 eyes) with nAMD and POAG were examined. The control group consisted of 39 healthy patients (39 eyes). The study included 24 patients (24 eyes) with stage IA POAG, 23 patients (23 eyes) with stage IIA POAG, 7 patients (7 eyes) with stage IIIA POAG. All patients with nAMD and POAG were given intravitreal injection of anti-VEGF drug: 35 patients received ranibizumab, 19 patients received aflibercept. Injections were performed monthly for 3 months. Ophthalmologic examination included visometry, biomicroscopy, retinal OCT using SPECTRALIS tomograph ('Heidelberg Engineering GmbH', Germany). VEP were recorded on EP-1000 Multifocal ('Tomey', Germany). All ophthalmologic studies were performed prior to administration of the anti-VEGF preparation and after the 3rd injection. RESULTS: After the third intravitreal injection of anti-VEGF drugs, best corrected visual acuity (BCVA) increased to 0.46±0.1 (p=0.001). According to OCT, central retinal thickness decreased by an average of 110.6 µm, the total volume of the retina decreased by 1.3 mm3, total thickness RNFL - by 3.8 µm (p<0.05). A decrease in the peak latency and an increase in the amplitude of the component P100 of VEP were noted. Statistically significant differences in indicators of VEP between antiangiogenic drugs ranibizumab and aflibercept were not detected (p>0.05). CONCLUSION: Intravitreal administration of anti-VEGF drugs ranibizumab and aflibercept has no negative influence on the functional state of the visual pathway in patients with nAMD and POAG. Intravitreal injections of ranibizumab and aflibercept can be considered a safe treatment option for patients with nAMD and POAG.

[Effect of intravitreal injections of ranibizumab and aflibercept on the retinal nerve fiber layer in patients with concomitant neovascular age-related macular degeneration and glaucoma]. / Vliianie intravitreal'nykh in''ektsii ranibizumaba i aflibertsepta na sloi nervnykh volokon setchatki pri sochetanii neovaskuliarnoi vozrastnoi makuliarnoi degeneratsii i glaukomy.

PURPOSE: To study the effect of ranibizumab and aflibercept on the thickness of retinal nerve fiber layer (RNFL) in patients with neovascular age-related macular degeneration (nAMD) and primary open-angle glaucoma (POAG). MATERIAL AND METHODS: The study included 62 patients (62 eyes) with nAMD and comorbid POAG. Patients were divided into two groups depending on the anti-VEGF treatment. The first group included 42 patients (42 eyes) who received injections of ranibizumab. The second group consisted of 20 patients (20 eyes) who received aflibercept. All patients received three injections of ranibizumab or aflibercept with one-month intervals. In addition to standard ophthalmic examination, patients underwent optical coherence tomography of the macular area and peripapillary RNFL. RESULTS: After anti-VEGF treatment, patients of both groups exhibited improvements expressed in reduced macular edema, increased visual acuity and absence of intraocular pressure (IOP) changes, as well as no statistically significant changes in the width and depth of excavation. There was a statistically significant decrease of peripapillary RNFL thickness in the temporal quadrant after treatment. CONCLUSION: The decrease of peripapillary RNFL thickness in the temporal quadrant occurs due to resorption of macular edema. In the absence of statistically significant changes in IOP, width and depth of excavation, intravitreal injections of ranibizumab and aflibercept can be considered safe treatment options for patients with concomitant nAMD and POAG.

[Pathogenesis and diagnostics of postsurgical macular edema]. / Patogenez i diagnostika posleoperatsionnogo makuliarnogo oteka.

Postsurgical macular edema, known as Irvine-Gass syndrome, is one of the possible causes of reduced visual acuity in phaco surgery. The literature review provides summarized data on pathogenesis, risk factors, clinical manifestations, classification and basic approaches to diagnosis based on modern techniques.

[Fluorescein angiography and optical coherence tomography findings in central fundus of myopic patients].

UNLABELLED: Myopia prevalence grows alike in many countries, including Russia, regardless of geographical and population conditions. AIM: to assess fundus changes in myopic patients at different ocular axial lengths by means of modern diagnostic tools. MATERIAL AND METHODS: The study enrolled 97 patients (194 eyes) aged 45 ± 20.17 years with myopia of different degrees. Besides a standard ophthalmic examination, all patients underwent fundus fluorescein angiography and optical coherence tomography. RESULTS: The occurrence of retinal pigment epithelium (RPE) atrophy (diffuse or focal) has been shown to increase with increasing ocular axial length. Only 27 eyes (28.1%) appeared intact. As myopia progression implies axial growth of the eye, it is associated with a more severe decrease in choroid, RPE, and photoreceptor layer thicknesses: the longer the anterior-posterior axis, the thinner the above mentioned fundus structures. Age-related changes in the fundus are also likely to be more pronounced in longer axes. Myopic traction maculopathy, which in our case appeared the main cause of increased retinal thickness, was diagnosed in 105 eyes, "outer" macular retinoschisis--in 40 eyes. CONCLUSION: Thus, modern diagnostic tools, such as fluorescein angiography and optical coherence tomography, enable objective assessment of the central fundus.

[Evaluating the efficacy of anti-VEGF therapy in patients with exudative age-related macular degeneration and concomitant glaucoma].

AIM: to evaluate the efficacy of anti-VEGF therapy in patients with exudative age-related macular degeneration (AMD) and glaucoma. MATERIAL AND METHODS: The study enrolled 117 patients (117 eyes) with exudative AMD and concomitant non-operated primary open-angle glaucoma (POAG). All patients were divided into several groups depending on their intraocular pressure (IOP) and stage of POAG. Hypotensive therapy included carbonic anhydrase inhibitors, beta-adrenergic antagonists (beta blockers) and alpha(2)-adrenergic agonists (alpha-2 mimetics). Lucentis (ranibizumab) was intravitreally injected thrice at monthly intervals. All patients underwent a standard ophthalmic examination, fluorescent retinal angiography, and optical coherence tomography. IOP was measured before the first and after the last injection by means of Icare PRO reboud tonometer. RESULTS: There was no statistically significant difference between groups Ia, IIa, Ib, and IIb in terms of IOP elevation. Glaucoma IIc and IIIa patients showed just a moderate increase in IOP that did not require regimen adjustment. There was, however, a single IIIb case of persistent IOP elevation, in which one-step penetrating trabeculectomy with intravitreal ranibizumab injection was later performed. Resolution of macular edema was achieved in all patients. Visual acuity (VA) varied between the groups demonstrating a tendency toward improvement in glaucoma Ia patients (p = 0.062) and stabilization in glaucoma IIa (p = 0.61), Ib (p = 0.07), and IIb (p = 0.29) patients. In some cases of low vision at baseline and subretinal fibrosis, VA changes were of no clinical significance. CONCLUSIONS: Intravitreal ranibizumab therapy proved effective in exudative age-related macular degeneration with concomitant glaucoma. Timely treatment of both AMD (i.e. before the development of subretinal fibrosis) and glaucoma contributes to therapeutic success in these patients.

Species identification of spider mites (Tetranychidae: Tetranychinae): a review of methods.

Spider mites (Acari: Tetranychidae) are dangerous pests of agricultural and ornamental crops, the most economically significant of them belonging to the genera Tetranychus, Eutetranychus, Oligonychus and Panonychus. The expansion of the distribution areas, the increased harmfulness and dangerous status of certain species in the family Tetranychidae and their invasion of new regions pose a serious threat to the phytosanitary status of agro- and biocenoses. Various approaches to acarofauna species diagnosis determine a rather diverse range of currently existing methods generally described in this review. Identification of spider mites by morphological traits, which is currently considered the main method, is complicated due to the complexity of preparing biomaterials for diagnosis and a limited number of diagnostic signs. In this regard, biochemical and molecular genetic methods such as allozyme analysis, DNA barcoding, restriction fragment length polymorphism (PCR-RFLP), selection of species-specific primers and real-time PCR are becoming important. In the review, close attention is paid to the successful use of these methods for species discrimination in the mites of the subfamily Tetranychinae. For some species, e. g., the two-spotted spider mite (Tetranychus urticae), a range of identification methods has been developed - from allozyme analysis to loop isothermal amplification (LAMP), while for many other species a much smaller variety of approaches is available. The greatest accuracy in the identification of spider mites can be achieved using a combination of several methods, e. g., examination of morphological features and one of the molecular approaches (DNA barcoding, PCR-RFLP, etc.). This review may be useful to specialists who are in search of an effective system for spider mite species identification as well as when developing new test systems relevant to specific plant crops or a specific region.

[Diagnostic and treatment patterns in management of male patients with nongonococcal urethritis: results of Russian multicentral cross-sectional study].

The aim of the study was to estimate the diagnostic and treatment patterns in the management of acute nongonococcal urethritis (NGU) in males in some cities of Russia. Retrospective cross-sectional study was conducted in 2009 in 5 centers of 4 cities in the Central Part of Russia (Kaluga, Pskov, Smolensk - 2 centres and Tula). The data on the diagnostic and treatment approaches to the management of NGU in male subjects >16 years old were collected and analyzed with the use of specially designed case report forms. 556 cases of acute urethritis were analyzed during the study. The diagnosis of NGU was confirmed in 401 cases. The average age of the patients was 29.8 years (16-68 years). The following diagnostic methods were used in 95% of the cases: urethral smear microscopy (314/82.4%), C. trachomatis - PCR (113/29.7%), ELISA (155/40.7%); T. vaginalis - PCR (106/27.8%); U. urealyricum and M. hominis, respectively - bacteriology (140/36.7% and 126/33.1%), PCR (110/28.9% and 108/28.3%); M. genitalium - PCR (110/28.9%). The treatment patterns included antimicrobials AMs alone in 60.3, and AMs + non-AMs in 37.8% of the cases. The most frequently prescribed AMs were azithromycin (27.5%), fluconazole (16.4%), doxycycline (13.6%), metronidazole (11.2%), ofloxacine (7.3%), ceftriaxone (4.4%), josamycin (4.2). According to the results use of the standard methods for NGU diagnosis was rather rare. The use of PCR for atypical pathogens was the following: C. trachomatis 29.7%, U. urealyticum 36.7%, M. hominis 28.9%, M. genitalium 28.3%. Doubtful culture methods were used for detection of U. urealyticum and M. hominis (36.7% and 33.1%). The AMs treatment in some cases was not in compliance with the up-to-date practical guidelines for STD and NGU.

[The safety of macrolide antibiotics: critical analysis].

Macrolide antibiotics are a safest group of antimicrobial drugs well tolerated by the patients. They have no hemato-, nephro- or cerebrotoxic action, do not cause chondro- or arthropathies, nor do they affect the photosensitizing system. Also, they are/free of many negative effects characteristic of other groups of antibiotics, such as anaphylactic reactions, severe toxico-allergic syndromes, and diarrhea. Most adverse effects of macrolides described in this review are functional disorders of various organs and systems, they are reversible and disappear after the termination of therapy. The beneficial safety profile of macrolides allows prescribing them for the treatment of various infections in inpatients and outpatients including children, pregnant women, elderly persons, and those suffering concomitant diseases.

[Decreased collagen stability as a response to the loss of structural integrity of thyroid cartilage].

The thermal behavior, birefringence properties, and the biochemical composition of thyroid cartilage tissues have been studied. The hyaline cartilage, which was visualized as a quasi-isotropic medium, was composed of type II collagen, which did not denature at temperatures up to 100 degrees C. However, in hyaline cartilage digested by trypsin, the denaturation of collagen occured at 60 degrees C. Collagen fibers in the perichondrium were composed of type I and II collagen and formed a highly organized anisotropic structure (birefringence about 4.75 x 10(-3)) with a melting temperature of about 65 degrees C. The temperature of collagen denaturation in perichondrium in the whole system perichondrium-hyaline cartilage increased up to 75 degrees C, indicating the immobilization of perichondrium collagen by the extracellular matrix of the hyaline constituent.

[SOS-induction in the presence of the plasmid pKM101 in the bacterial cells Escherichia coli K12].

Induction of transcription by the plasmid pKM101 (mutability mediating derivate of the plasmid R46) of the sfiA gene controlling cell division and of the fruA gene encoding the fructose specific enzyme II of the phosphoenolpyruvate-phosphotransferase system in intact cultures of Escherichia coli was studied. The genes under study were fused to the bacteriophage Mu dl (Ap lac). Activation of the sfiA gene, a typical member of the SOS-regulon, was demonstrated to depend on the key genes of the SOS-system-recA and lexA. In contrast, the fruA gene that is non-inducible by the UV-light, a classical SOS-inducing agent, is not activated by the presence of the plasmid pKMIO1 in the bacterial cells. The data obtained suggest that the presence of pKMIO1 plasmid in the Escherichia coli cells induces a SOS-signal as a consequence of the plasmid DNA replication or its conjugative transfer.

The inventory of antibiotics in Russian home medicine cabinets.

The objective of this study was to inventory the stock of antimicrobials in the home medicine cabinets (HMCs) of the general population in Russia and to find out for which indications people report that they would use antibiotics without a physician's recommendation. The research was performed in 9 Russian cities by physicians who visited households. An inventory of antibiotics in HMCs was made, and respondents were asked about instances in which they would choose automedication with antibiotics. We found that 83.6% of families had antibiotics for systemic use in HMCs. The most common antibiotics in HMCs were trimethoprim-sulfamethoxazole (46.3% of HMCs), ampicillin (45.1%), chloramphenicol (32.7%), erythromycin (25.5%), and tetracycline (21.8%). The major indications for automedication with antibiotics were acute viral respiratory tract infections (12.3% of total indications), cough (11.8%), intestinal disorders (11.3%), fever (9%), and sore throat (6.8%). According to this study, antibiotics are widely stocked among the general population in Russia, and people use antibiotics in an uncontrolled and imprudent manner.

The effect of plasmid pKM101 on umuDC gene function enhancing precise excision of transposons.

Mutation in the thr gene with the highest UV-induced reversion frequency has been chosen from a number of mutations arisen from insertion of transposon Tn10 into the umuDC- Salmonella typhimurium. This mutation has been transferred by transduction into the Salmonella strain carrying E. coli umuDC+ genes. umuDC- and umuDC+ Salmonella strains, bearing the same insertion mutation, were used to study the effect of umuDC genes and of plasmid pKM101 on spontaneous and UV-induced precise excision of Tn10. This process, like point mutagenesis, is shown to be umuDC-stimulated. Plasmid pKM101 eliminates the effect of umuDC+ genes on UV-induced Tn10 precise excision, in contrast to its effect on point mutagenesis, and does not enhance spontaneous precise excision of Tn10.

Effect of plasmid pKM101 in ultraviolet irradiated uvr+ and uvr- Escherichia coli.

The effect of plasmid pKM101 on UV irradiated excision proficient and excision deficient cells was investigated. The plasmid increased the survival of excision proficient cells while partially inhibiting thymine dimer excision. The frequency of mutations was almost unchanged. In excision deficient cells the effect of the plasmid on survival was less pronounced while cell mutability was increased. Our data indicate that the mucAB genes (carried by the plasmid) influence the two types of cells in a different way.

Precise excision of transposons and point mutations induced by chemicals.

The ability of 23 chemicals (carcinogens and non-carcinogens) to induce precise excision of Tn10 and point mutations was studied in experiments with a single strain. The mutation assay was shown to detect a wider spectrum of genotoxic agents than the assay of Tn10 precise excision. The latter was induced only by potent SOS mutagens, which is in accordance with data on the SOS dependence of the induction of precise excision of Tn10. The precise excision assay as an additional test contributing to the knowledge of particular features of the action of a tested mutagen is discussed. The induction of precise excision of Tn10 by pyrene (and its failure to induce point mutations in this strain) demonstrates the value of using the transposon excision assay in cases of 'problem' mutagens.

[SOS-induction of the RP4 plasmid tet-determinant]. / SOS-indutsibel'nost' tet-determinanty plazmidy RP4.

Induction of the tetracycline-resistance genes function by the inducer of the DNA-repair and mutability SOS-system, UV-light, has been tested. Activity of the tet-genes residing on the plasmid RP4 in Escherichia coli cells has been shown to be inducible by the low doses of tetracycline as well as by the mutagenic doses of UV-light. The induction was quantitatively registered by measuring the activity of beta-galactosidase of bacteriophage Mud1 (Ap, Lac) inserted into the tet-genes of the plasmid RP4. The bacteriophage integration inactivates the tet-genes function of the constructed plasmid fusing the lac-operon to a promoter of inactivated genes. Precise excision of bacteriophage restores the activity of the tet-genes proving together with the plasmid DNA-restriction analysis the fusion of tet-promoter with Iac-operon. The tet-genes of RP4 are concluded to be a part of the SOS-regulon, a set of genes inducible by the conditions harming the bacterial cell. Preliminary data on the mutagenic activity of tetracycline obtained in the bacterial test-system of mutagens are discussed.